Mentoring is an entirely different thing than fixing bikes. You have to think about exactly what you want to teach. Plan the experience. And give the student enough opportunity to experience the pitfalls and try to figure them out on their own. Then we'd discuss what they did, why, and maybe how to do it more easily next time.

If I'm fixing bikes, I don't want anybody looking over my shoulder or asking questions. I just want to get on with the job at hand.

I donn't mind doing either one, but I absolutely hate any attempt to mix the two.